Refrigerating apparatus



2 Sheets-Sheet 1 R. K. MILLER REFRIGERATING APPARATUS Original FiledJuly 19, 1934 May 4, 1937.

n T. U I II I I l 7 I I l I I I l I I l D Q I M 5 v 7 2 May 4, 1937.

R. K. MILLER REFRIGERATING APPARATUS Original Filed July 19, 1954 2Sheets-Sheet 2 his SMW M Patented May 4, 1937 UNITED STATES 2,0 9,377REFRIGERATING APPARATUS Ralph K. Miller, Dayton, Ohio, assignor toGeneral Motors Corporation, Dayton, Ohio, a corporation of DelawareApplication July 19, 1934, Serial No. 736,010 Renewed October 8, 1935 14Claims. (01. 62-126) fIhis invention relates to refrigerating apparatusand particularly to cooling elements or evaporators of such apparatus.

In mounting an evaporator within a food storage compartment, of arefrigerator cabinet to be cooled, in the top central portion of thecompartment and constructing the evaporator so that refrigerant isdirected from a liquid refrigerant inlet connection directly through arefrigerated shelf or through a plurality of shelves prior to beingcirculated or distributed to the walls of the evaporator it has beenfound that bottled beverages placed adjacent the walls of the evaporatorin the upper portion of a food 5 storage compartment are not quickly orefficiently cooled to the proper low temperature. This difficulty arisesfrom the fact that refrigerant passing through passages in the sidewalls of the evaporator has already completely evap- 20 orated or hasabsorbed all the heat it is capable of absorbing and is thereforeincapable of absorbing additional heat at the upper portion or at thetop of the side walls of the evaporator. This therefore inherentlyresults in the presence 35 of a warm pocket or a portion adjacent thetop of the food compartment which is of a higher temperature than otherportions of the compartment and into which the bottles extend. It isthis difficulty that the present invention m purports to overcome toproduce an efiicient evaporator and consequently efficient refrigerationor uniform cooling of all portions of a food storage compartment.

An object of my invention is to provide a sheet metal evaporatorconstruction having, between the liquid refrigerant inlet and arefrigerant outlet connections thereof, an improvedrefrigerant flowcircuit including a portion or duct connected in series with the inletconnection and U another portion including a plurality of interconnectedpassages connected in parallel circuit relation with the refrigerantoutlet connection. In carrying out the foregoing object, it is a furtherobject of my invention to form one extended portion and at least a partof the other portion of the refrigerant flow circuit, through theevaporator, between sheet metal portions bent to provide wa'ls of afreezing chamber and to utilize one portion of the refrigerant flowcircuit, connected in series with the refrigerant inlet connection, asan extended low temperature refrigerated wall portion at the top andacross substantially the depth of the evaporator and another portionthereof as a sharp freezing zone or refrigerated shelf and to utilizethe passages of the other circuit, connected in parallel circuitrelation with the refrigerant outlet connection, as a refrigerantdistributing portion or cooling zone for the evaporator.

Further objects and advantages of the present 5 invention will beapparent from the following description, reference being had to theaccompanying drawings, wherein a preferred form of the, presentinvention is clearly shown.

In the drawings:

Fig. 1 discloses a refrigerator cabinet with the access door to the foodstorage compartment thereof in open position and showing an evaporatorconstructed according to the present invention installed therein;

Fig. 2 is an enlarged front view of my improved evaporator showing aplurality of compartments formed therein by refrigerated shelves;

Fig. 3 is an elevational view of the left side of .the evaporator shownin Fig. 2;

Fig. 4 is a fragmentary elevational view of the right side of theevaporator shown in Fig. 2;

Fig. 5 is a view of the bottom of the evaporator;

Fig. 6 is a fragmentary sectional view through the evaporator taken online 66 of Fig. 4; and

Fig. 7 is a top view of the evaporator showing a plan view of one of therefrigerated shelves located within the freezing chamber of theevaporator. I

For the purpose of illustration, I have shown in Fig. 1 of the drawings,an evaporator 20 constructed according to my invention mounted in arefrigerator cabinet 2| of any suitable construction or design.Preferably the cabinet comprises an insulated food storage compartment22 having a door 23 providing access thereto and a machine compartment(not shown) disposed below the compartment 22. The refrigerantliquefying unit, of the refrigerating system connected with theevaporator 20, may be of any suitable type and is adapted to be mountedin the machine compartment disposed below the food storage compartment.Mechanical refrigcrating apparatus of the type herein mentioned are wellknown to those familiar with the art and therefore need no furtherdescription.

My invention is directed to a finished evapm rator which is produced byuniting, in any suitable manner, superimposed sheet metal portions orplates 25 and 26 (see Fig. 6) to produce a double walled structurevhaving refrigerant passages formed between the sheet metal portions orplates. The double walled structure, formed municate with the space orpassage between the sheets or plates 25 and 26 of-the double walledmember. Refrigerant inlet connection 3| is connected with a refrigerantflow control device or expansion valve 33 of any conventional orwellknown design and the device or valve 33 governs the flow ofrefrigerant to the evaporator in any well-known manner. In order toextend a portion of the series refrigerant flow circuit through one ormore of the walls 21 and 28 of the evaporator 28 to precool the aircooling walls or to rapidly reduce the temperature at the top thereof, arefrigerant conveying duct 35 is formed by and located between the sheetmetal members 25 and 25 on the upper left hand side of the evaporator orwall 21. The refrigerant duct 35 communicates with the liquidrefrigerant inlet connection or pipe 3| at the rear of the evaporator 28and the duct extends horizontally across substantially the width of theside wall. The duct 35 has a reverse turn 36 provided near the frontportion of the evaporator so as to form a loop and permit the tail endof the duct 35 to extend back towards the rear of the evaporator (seeFig. 3). The outlet or tail end of duct 35 is connected with a pipe 31(see Figs. 2, 3, and '7) which pipe extends across the top of thefreezing chamber and connects with a second refrigerant conveying ductformed by and located between the sheet metal members or plates 25 and28 on the upper right hand side of the evaporator or along the wall 28thereof. The duct 38 extends horizontally across substantially the widthof the side wall and communicates with an outlet pipe 39 at the rear ofthe evaporator 28. Duct 38 has a reverse turn 48 provided near the frontof the evaporator so as to form a loop and permit the tail end of theduct with a pipe 41 which connects with the inlet to 38 to extend towardthe back of the evaporator (see Fig. 4). The'pipe 39 connected with theoutlet end of duct 38 extends downwardly to a refrigerated shelf.

In order to provide a freezing portion and a refrigerant distributing orair cooling portion for the evaporator the refrigerant flow circuitincludes a means in the form of a horizontally disposed shelf or shelves4| and 42 respectively which divide the interior of the freezingchamber, formed by the walls 21', 28 and 29 of the evaporator, into aplurality of superimposed compartments. Each of the shelf means 4| and42 comprises two superimposed sheet metal plates or members 43 and 44(see Fig. 6) secured together in any suitable manner. The lower of theplates or members 44 of shelves 4| and 42 have formed thereindepressions which, when the plates 43 and 44 are secured together,provide a serpentine refrigerant passage or duct 45 extendinghorizontally through the chamber. The refrigerant duct 45 in shelf 4|has its inlet communicating with the pipe 39 and has its outletcommunicating duct 45 provided in shelf 42. A pipe 48 connects theoutlet of duct 45, in shelf 42, with a refrigerant distributing header(fr'manifold passage 5| formed by and located between the sheet metalplates or members 25 and 25 in the bottom wall 29 of the evaporator 28(see Fig. 5). .A plurality of refrigerant conveying conduits 53 areformed by and located between the plates 25 and 26 and are connected inmultiple with the header or manifold passage 5| and extend around atleast a portion of the bottom wall 29 and upwardly over a portion of theside wall 21 of the evaporator 28. A second set of a plurality ofrefrigerant conduits 54 are formed by and located between the sheetmetal members 25 and 26 and are connected in multiple with the header ormanifold passage 5| and extend around at least a portion of the bottomwall 29 and upwardly over a portion of the side wall 28 of theevaporator. Both sets of the plurality of refrigerant conduits 53 and 54communicate with one or more headers or manifold passages 55 formed byand located between the plates 25 and 26 in the side walls 21 and 28 cfthe evaporator. One of each of the headers 55 located on opposite sidewalls of the evaporator and preferably the top header has a pipe 56connecting the headers or manifold passages 53 and 54 with the outletpipe 32.

The refrigerated shelves 4| and 42 may be seecured to the side walls 21and 28 of the evaporator 28 in any suitable manner and the evaporatortogether with these shelves and the pipe connections may be coated orplated with any suitable material, for example, they may be chromiumplated. Any suitable bracket or mounting means may be provided formounting the evaporator 28 in the food storage compartment 22 of thecabinet 2|. It is to be understood that the foregoing definedrefrigerant conveying ducts, conduits, passages, or header manifolds aresealed about their edges by uniting the metal members 25 and 26 togetheradjacent thereto.

From the above description of the refri erant conveying ducts, conduits,passages or header .manifolds it may be seen that I have provided arefrigerant flow circuit through the sheet metal evaporator 28, betweenthe liquid refrigerant inlet and the refrigerant outlet connections 3|and 32 thereof, which includes an extended portion communicating inseries with the liquid refrigerant inlet connection 3| and anotherportion communicating in multiple or in parallel circuit relation withthe outlet connection 32 and that I have extended a portion of theseries flow circuit through the walls of the evaporator so as tocirculate refrigerant directly from the flow control device or expansionvalve 33 through a portion of these wallsprior to circulating therefrigerant to the refrigerated shelves. More fully explaining thisrefrigerant flow circuit, between the refrigerant inlet and outletconnections 3| and 32 of the evaporator, the portions connected inseries. with the refrigerant inlet connection 3| includes therefrigerant duct 35, pipe 31, duct 38, pipe 39, conduit 43 formed inshelf 4|, pipe 41, conduit 45' formedin shelf, and a pipe 48 which leadsto the lower distributing header or manifold passage 5|. The portion ofthe refrigerant flow circuit communicating in parallel circuit relationwith the. outlet connection 32 of the evaporator includes thedistributing header or manifold passage 5|, the refrigerant conduits .53and 54 and the headers or manifolds 55.

Since refrigerant is first circulated from the inlet pipe 3| through therefrigerant ducts 35 and 38 these ducts and the portions of the plates25 and 25 immediately surrounding the ducts provide a very cold zone inthe top portion of the walls of the evaporator and thus prevent theformation of warm pockets or pockets of a temperature higher than otherlocalities within the food storage compartment 22. Thus bottledbeverages will be quickly and efficiently cooled when placed inanupright or vertical position adjacent walls of my improved evaporator.The refrigerant after passing through the refrigerant ducts and 38 is,as before stated, directed to the refrigerant passage in the upper shelf4| and thence to the refrigerant passage 45 in the lower shelf H2. Theshelves Hand 42 thus provide fast freezing supports or zones for icetrays or the like 58 (see Fig. 1) adapted to contain substances to befrozen. Also since refrigerant is circulated in a series path to thebottom wall 29 of the evaporator this bottom wall provides a support fora tray or receptacle for rapidly chilling desserts and the like. Themultiple flow of refrigerant or parallel circuit flow through conduits53 and 56 provide refrigerated walls for the evaporator which cool andcause circulation of air within the food storage compartment 22 of therefrigerator cabinet 2|.

From the foregoing it will become apparent that. I have provided a novelsheet metal evaporator having an improved and an efiicient refrigerantflow circuit incorporated therein, between the liquid refrigerant inletconnection and the refrigerant outlet connection thereto, whichuniformly cools all portions of the interior of a food storagecompartment to approximately the same temperature, thus preventing theformation ofwarm pockets and at the same time provides a quick freezingor fast freezing zone and'another portion provides the evaporator withair cooling wall zones. My improved evaporator is not only veryefficient during the process of producing refrigeration but is also veryefficient for effecting quick and uniform defrosting of the wallsthereof.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a plurality of walls of a freezing chamber,a refrigerant conveying duct extending in a horizontal directionsubstantially across the upper part of a certain wall of said chamberand having a refrigerant inlet connection, a header or manifold passagedisposed below said refrigerant duct and extending in a directionsubstantially parallel thereto along a certain wall of said chamber,means for connecting said duct with said header or manifold passage, aplurality of refrigerant conveying conduits communicating with saidheader or manifold passage, said refrigerant duct, said header ormanifold passage and said refrigerant conduits being formed by andlocated between the sheet metal portions of the chamber walls, and saidduct, said header or manifold and the connecting means therebetweentogether with said conduits being arranged to provide a refrigerant flowcircuit through said evaporator including an extended portionv in serieswith said inlet connection and another extended portion comprising saidconduits connected in parallel circuit relation with each other andhaving a common outlet connection, I

- 2. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide aplurality of walls of a freezing chamber,a refrigerant conveying duct extending in a horizontal directionsubstantially across the upper part of a certain wall of said chamberand having a refrigerant inlet connection, a header or manifold passagedisposed below said refrigerant duct. and extending in a directionsubstantially parallel thereto along a certain wall of said chamber,means for connecting said duct with said header or manifold passage, aplurality of refrigerant conveying conduits communicating with saidheader or manifold passage, said refrigerant duct, said header ormanifold passage and said refrigerant conduits being formed by andlocated between the sheet metal portions of the chamber walls, and saidduct, said header or manifold and the connecting means therebetweentogether with said conduits being arranged to provide a refrigerant flowcircuit through said evaporator including an extended portion in serieswith said inlet connection and another extended portion comprising saidconduits connected in parallel circuit relation with each other andhaving a common outlet connection, said connecting means between saidduct and said header or manifold passage including a refrigerated shelfor shelves disposed within'said freezing chamber for receiving andsupporting thereon a receptacle adapted to contain a substance to becongealed or frozen.

3. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a vertical wall and a horizontal bottomwall of a freezing chamber, a refrigerant conveying duct extending in ahorizontal direction substantiallyacross the upper part of the verticalwall of said chamber and having a refrigerant inlet connection, a headeror manifold passage extending in a direction substantially parallel tosaid refrigerant duct along the bot tom wall of said chamber, means forconnecting said duct with said header or manifold passage, a pluralityof refrigerant conveying conduits communicating with said header ormanifold passage, said refrigerant duct, said header or manifold passageand said refrigerant conduits being formed by and located between thesheet metal portions of the chamber walls, and said duct, said header ormanifold passage and the connecting means therebetween together withsaid conduits being arrangedto provide a refrigerant flow circuitthrough said evaporator includ-' ing an extended portion in series withsaid inlet connection and another extended portion comprising saidconduits connected in parallel circuit relation with each other andhaving a common outlet connection.

4. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a vertical wall and a horizontal bottomwall of a freezing chamber, a refrigerant conveying duct extending in ahorizontal direction substantially across the upper part of the verticalwall of said chamber and having a refrigerant inlet connection, a headeror manifold passage extending in a direction substantially parallel tosaid refrigerant duct along the bottom wall of said chamber, means forconnecting said duct with said header or manifold passage, a pluralityof refrigerant conveying conduits communieating with said header ormanifold passage, said refrigerant duct, said header or manifold passageand said refrigerant conduits being formed by and located between thesheet metal portions of the chamber walls, and said duct, said header ormanifold passage and the connecting means therebetween together withsaid conduits being arranged to provide a refrigerant flow circuitthrough said evaporator including an extended portion in series withsaid inlet connection and another extended portion comprising saidconduits connected in parallel circuit relation with each other andhaving a common outlet connection,-said connecting means between saidduct and said header or manifold passage including a refrigerated shelfor shelves disposed within said freezing chamber for receiving andsupporting thereon a receptacle adapted to contain a substance to becongealed or frozen.

5. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a vertical wall and a horizontal bottomwall of a freezing chamber, a refrigerant conveying duct extending in ahorizontal direction substantially across the upper part of the verticalwall of said chamber and having a refrigerant inlet connection, a headeror manifold passage extending in a direction substantially parallel tosaid refrigerant duct along the. bottom wall of said chamber, means forconnecting said duct with said header or manifold passage, a

plurality of refrigerant conveying conduits communicating with saidheader or manifold passage and traversing a portion of the bottom and ofthe vertical wall of said chamber, said refrigerant duct, said header ormanifold passage and refrigerant conduits all being formed by andlocated between the sheet metal portions of the chamber walls, and saidduct, said header or manifold passage and the connecting meanstherebetween together with said conduits being arranged to provide arefrigerant flow circuit through said evaporator including an extendedportion comprising said conduits connected in series with said inletconnection and another outlet, at second refrigerant conveying ductextending substantially across the upper part of the other of saidupright chamber walls in a substantially horizontal direction and havinga refrigerant inlet and a refrigerant outlet, means for connecting therefrigerant outlet of said first named refrigerant duct with therefrigerant inthe chamber walls, and said ducts together with theconnecting means therebetween, said header or manifold passage togetherwith the means connecting same with said last named duct and saidconduits being arranged to provide a refrigerant flow circuit throughsaid evaporator including an extended portion in series with said inletconnection to said first named duct and another extended portioncomprising said conduits connected-in parallel circuit relation witheach other and having acommon outlet connectlon.

'7. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide two upright walls and a bottom wall of afreezing chamber, a refrigerant conveying duct extending substantiallyacross the upper part of one of said upright chamber walls in asubstantiallyhorizontal direction and having a refrigerant inletconnection and a refrigerant outlet, a second refrigerant conveying ductextending substantially across the upper part of the other of saidupright chamber walls in a substantially horizontal direction and havinga refrigerant inlet and a refrigerant outlet, means for connecting therefrigerant outlet of said first named refrigerant duct with therefrigerant inlet of said second named refrigerant duct, a headerormanifold passage extending in a direction substantially parallel tosaid refrigerant ducts along the bottom wall of said chamber, means forconnecting the refrigerant outlet of said second named refrigerant ductwith said header or manifold-passage, a plurality of refrigerantconveying conduits communicating with said header or manifold passage,said refrigerant ducts, said headeror, manifold passage and saidrefrigerant conduits being formed by and located between the sheet metalportions of the chamber walls, and said ducts together with theconnecting means therebetween, said header or manifold passage togetherwith the means connecting same with said last named duct and saidconduits being arranged to provide a refrigerant flow circuit throughsaid evaporator including an extended portion in series .with said inletconnection to said first named duct and another extended portioncomprising said conduits connected-in parallel circuit relation witheach other and having a common outlet connection, said connecting meansbetween said second named refrigerant duct and said header or manifoldpassage comprising a refrigerated shelf or shelves disposed within saidfreezing chamber for receiving and. supporting thereon a receptacleadapted to contain a substance to be congealed or frozen.

8. An evaporator comprising sheet metal portions secured together andarranged to provide opposed upright walls of a freezing chamber, asingle refrigerant duct having a portion thereof extending across one ofthe opposed freezing chamber walls and having another portion thereofextending across the other of said opposed freezing chamber walls, saidduct having an inlet connection in the upper part of said one of saidopposed upright freezing chamber walls, said duct being arranged toconvey refrigerant from said inlet connection continuously in'anundivided path first across said one of said opposed upright freezingchamber walls and thence across,

said other of said opposed upright walls, a header or manifold passagedisposed below the inlet connection to said duct and extending along acertain wall of said chamber and having a connection with said singleduct, a plurality of refrigerantv conveying conduits communicating withsaid header or manifold passage, said header or manifold passage, saidrefrigerant conduits and at least said portions of said singlecontinuous refrigerant duct being formed by and located between thesheet metal portionsof the chamber walls, and said single continuousduct. said heador frozen.

9. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a plurality of walls of a freezing chamber,a refrigerant conveying duct extending in a horizontal directionsubstantially across the upper part of a certain wall of said chamberand having a refrigerant inlet connection, a header or manifold passagedisposed below said refrigerant duct and extending in a directionsubstantially parallel thereto along a certain wall of said chamber,means for connecting said duct with said header or manifold passage, asecond header or manifold passage disposed below said refrigerant ductand above'said first named header or manifold passage and extending in adirection substantially parallel to said refrigerant duct and said firstnamed header or manifold passage along a certain wall of said chamberand having an outlet connection, a plurality of refrigerant conveyingconduits extending between and communicating with each of said headersor manifolds, said refrigerant duct, said headers or mani fold passagesand said refrigerant conduits being formed by and located between thesheet metal portions of the chamber walls, and said duct, said headersor manifolds and the conduits therebetween together with the meansconnecting the duct with said first named header or manifold beingarranged to provide a refrigerant flow circuit through said evaporatorincluding an extended portion in series with said inlet connection andanother extended portion comprising said conduits. connected in parallelcircuit relation with each other by said headers or manifold passagesand communicating with said outlet connection.

10. An evaporator comprising superimposed sheet metal portions, securedtogether and bent to provide a plurality of walls of a freezing chamber,a refrigerant conveying duct extending in a horizontal directionsubstantially across the upper part of a certain wall of said chamberand having a refrigerant inlet connection, a header or manifold passagedisposed below said refrigerant duct and extending in a directionsubstantially parallel thereto along a certain wall of said chamber,means for connecting said duct with said header or manifold passage, 8.second header or manifold passage disposed below said refrigerantductand above said first named header or manifold passage and extending in adirection substantially parallel to said refrigerant duct and said firstnamed header or manifold passage along a-certain wall of said chamberand having an outlet connection, a plurality of refrigerant conveyingconduits extending between and communicating with each of said headersor manifolds,

said refrigerant duct, said headers or manifold;

passages and said refrigerant conduits being formed by and locatedbetween the sheet metalportions of the chamber walls, and said duct,said headers or manifolds and the conduits therebetween together withthe means connecting the duct with said first named header or manifoldbeing arranged to provide a refrigerant flow circuit through saidevaporator including an extended portion in series with said inletconnection and another extended portion comprising said conduitsconnected in parallel circuit rela tion with each other andcommunicating with said outlet connection, said connecting means betweensaid duct and said first named headeror manifold passage including arefrigerated shelf or shelves disposed within said freezing chamber forreceiving and supporting thereon a receptacle adapted to contain asubstance to be congealed or frozen.

11. An evaporator comprising superimposed erant inlet connection, aheader or manifold passage extending in a direction substantiallyparallel to said refrigerant duct along the bottom wall of said chamber,means for connecting said duct with said header or manifold passage, asecond header or manifold passage disposed below said refrigerant ductand extending along the vertical wall of said chamber in a directionsubstantially parallel to said refrigerant duct and said first namedheader or manifold passage and having an outlet connection, a pluralityof refrigerant conveying conduits extending between and communicatingwith each of said headers or manifold passages, said refrigerant duct,said headers or manifold passages and said refrigerant conduits beingformed by and located between the sheet metal portions of thechamberwalls, and said duct, said headers or manifolds and the conduitstherebetween together with the means connecting the duct with said firstnamed header or manifold being arranged to provide a refrigerant flowcircuit through said evaporator including an extended portion in serieswith said inlet connection and another extended portion comprising saidconduits 'connected in parallel circuit relation with each other by saidheaders or manifold passages and communicating with said outletconnection.

12. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide a vertical wall and a horizontalbottom.wall of a freezing chamber, a refrigerant conveying ductextending in a horizontal direction substantially across the upper partof the vertical wall of said chamber and having a refrigerant inletconnection, a header or manifold passage extending in a directionsubstantially parallel to said. refrigerant duct along the bottom wallof said chamber, means for connecting said duct with said header ormanifold passage, a second header or manifold passage disposed belowsaid refrigerant duct and extending along the vertical wall of saidchamber in a direction substantially parallel to said refrigerant ductand said first named header or manifold passage and having an outletconnection, a plurality of refrigerant conveying conduits extendingbetween and communicating with each of said headers or connecting theduct with said first named header or manifold being arranged to providea refrigerant fiow circuit through said evaporator including an extendedportion in series with said inlet connection and another extendedportion comvprising said conduits connected in parallel ciring andsupporting thereon a receptacle adapted to contain a'substance tobe-congealed or frozen.

13. An evaporator comprising superimposed sheet metal portions securedtogether and bent to provide two upright walls and a bottom wall of afreezing chamber, a refrigerant conveying duct extending substantiallyacross the upper part of one'of said upright chamber walls in asubstantially horizontal direction and having a refrigerantinlet'connection and a refrigerant outlet, a'second refrigerantconveying duct extending substantially across the upper part of theother of said upright chamber walls in a substantially horizontaldirection and having a refrigerant inlet and a refrigerant outlet, meansfor connecting the refrigerant outlet of said fiirst named refrigerantduct with the refrigerant inlet of said second named refrigerant duct, aheader or manifold passage extending in a direction substantiallyparallel to said refrigerant ducts along the bottom wall of saidchamber, means for connecting the refrigerant outlet of said secondnamed refrigerant duct with said header or manifold passage, a secondheader or manifold passage extending in a direction substantiallyparallel to said refrigerant ducts andto said first named header ormanifold passage along one: of the upright walls of said chamber, aplurality of refrigerant conveying conduits extending between andcommunicating with both of said headers or manifold passages, an outletconnection for said second named header or manifold passage, saidrefrigerant ducts, said headers or manifold passages and saidrefrigerant conduits being formed by and located between the sheet metalportions of the chamber walls, and said ducts together with theconnecting means therebetween, said headers or manifold passagestogether with the means connecting the first named header or manifoldpassage with said last named duct and said conduits being arranged to,provide a refrigerant flow circuit through said evaporator including anextended portion in series with said inlet connection to said firstnamed duct and another extended portion comprising said conduitsconnected in parallel circuit relation with each other by said headersor manifold passages and communicating with the outlet connection ofsaid second named'header ormanifold passage.

14. An evaporator comprising superimposedsheet metal portions securedtogethervandbent to provide two upright walls and a bottom wall of afreezing chamber, a refrigerant conveying duct extending substantiallyacross the upper part of one of said upright chamber 'walls-in asubstantially horizontal direction and having a refrigerant inletconnection and a refrigerant outlet, a second refrigerantconveying ductexnamed refrigerant duct with said header or manifold passage,,a secondheader or manifold pas sage extending in a direction substantiallyparallel to said refrigerant ducts and to said first named header ormanifold passage along one of the upright walls of said chamber, aplurality of refrigerant conveying conduits extending between andcommunicating with both of said headers or manifold passages, an outletconnection for said second named header or manifold passage, saidrefrigerant ducts, said headers or manifold passages and saidrefrigerant conduits being formed by and located between the sheet metalportions of the chamber walls, and said ducts together with theconnecting means therebetween, said headers or manifold passagestogether with the means connecting the first named header or manifoldpassage with said last named duct and said conduits being arranged toprovide a refrigerant flow circuit through said evaporator including anextended portion in series with said inlet connection to said firstnamed duct and another extended portion comprising said conduitsconnected in parallel circuit relation with each other by said headersor manifold passages and communicating with the outlet connection ofsaid second named header or manifold passage, said I connecting meansbetween said second named refrigerant duct'and' said first named headeror manifold passage comprising arefrigerated shelf or shelves disposedwithin said freezing chamber for receiving and supporting thereon areceptacle tending substantially across the upper part of the adapted tocontain a substance'to be congealed or 1

